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Levers and Equivalents.

which can be easily proved by the levers shewn below.   Generally,
then, for toothed gearing with wheel and axle,

......... .,    ,'•   , .W      followers      handle rad.

Mech. Adv. — = -j-.------ x-------—~~

P        drivers         barrel rad.

the wheels being estimated by teeth, radius, or diameter.

'   l^J^L

Belting is a substitute for toothed gearing, as shewn in the
Diagram, a crossed belt giving the same direction of motion
j&s Ane pair of wheels. N.B.,—If speeds only are to be reckoned,
the wheel andfaxle does not enter into the calculation.

T}ie Brock arid Tackle (Fig. 439).~Neglectirig friction)
the cord has the same tension throughout, and there are (in the
case shewn) six pulls on the weight, each equal to P.

,,   ,   AJ    W      6                           No. of cords

^ .,% .Meet. Adv. ~ =. -    or generally == ——._

v......      '     '    '                 ' W   ' '2

;J   'In-any -movable pulley M,   p- = - because W only rises half

of P, as shewn.    (Seep. 741.)